I setup the uni-directional streams replication of a schema. The streams is running fine and the start SCN and required checkpoint SCN were moving forward. I set capture retention to 3 days. But, the required checkpoint SCN, start SCN and fist SCN are not moving forward from past four days. The streams capture and apply running perfectly and it's applying all the latest records.

But, if the streams is restarted for any case, the capture may look for the old archivelogs since the required checkpoint SCN is not moving forward. What is possible reason for it and how to resolve it?. Could someone explain please?.

The First SCN, Required Checkpoint SCN, start SCN are hanging again. I don't see any 2PC pending transactions. The streams apply is working fine. But, these SCNs are not moving forward on capture side. Any idea why?.